Field of the Invention
The present invention relates to improved clad optical conduit and a method of production therefor. The improved optical conduit and method of manufacture of the present invention concern cylindrical light emitting conduits which emit light from their outer circumferential surface in a more optically efficient manner, with a greater light intensity and in a more uniform manner than previously known. Optical efficiency refers to the ratio of light output to light input for a given tube length and cross section. The conduit of the present invention includes clad optical conduits in which a glass or polymeric core having a relatively high refractive index is surrounded by a cladding of a relatively low refractive index and a gap therebetween is created and is filled with air or some other material having a relatively low refractive index compared to that of the core.
Clad optical conduit of the general type within the field of the present invention, and their manufacture, are known, and are generally disclosed, for example, in U.S. Pat. No. 3,641,332 and Application Ser. No. 300,202, filed Jan. 23, 1989, for "Method, Apparatus and Composition of Matter For a High Temperature Plastic Light Conduit". A copy of Ser. No. 300,202 is filed herewith, to provide basis for subsequent incorporation by amendment. Although such clad optical conduit has been known for many years, a number of problems remain even with the improved conduit as described in application Ser. No. 300,202. Such remaining known problems include relatively poor optical efficiency, intensity and poor uniform light emittance at the outer peripheral surface of the cladding which surrounds the inner light transmitting core.